Concentric mandrel for intermittent gas lift with accumulation chamber

ABSTRACT

The invention features a concentric mandrel and suspension element, which uses the same gas-lift valve used in a side bag mandrel. The application of the invention is proposed for wells with very low static pressure that operate with an intermittent pneumatic lift, enabling the production in these wells. The development of a concentric mandrel and the respective macaroni suspension element (1), allows the use of an insertable accumulation chamber, and at the same time allows the replacement of the gas-lift valve to be carried out with a wire unit, thus avoiding rig interventions, which are more expensive and time consuming.

FIELD OF INVENTION

The lifting system proposed here is intended for wells with very low static pressure (close to head pressure) that operate with intermittent pneumatic lifting.

DESCRIPTION OF THE STATE OF THE ART

Intermittent pneumatic wells are equipped in the traditional way with a packer plug, a standing valve and a gas-lift valve that is positioned above the packer. This type of installation provides relatively low flow pressure but can reduce or even impede production from wells with very low static pressure. The use of an insertable chamber is an alternative to circumvent this problem, but it had the drawback of not allowing the gas-lift valve to be changed using a wire unit (without rig intervention).

One of the drawbacks of using pneumatic methods in artificial lifting in oil wells is the difficulty in reducing the bottom flowing pressure, which restricts their use to wells with reasonable static pressure. In this sense, intermittent pneumatic methods such as GLI or GLP, although restricted to low-flow wells, represent an advance over GLC by providing a lower bottom pressure, albeit one that is still higher than that which can be obtained by pumping methods, where it is theoretically possible to operate with a bottom pressure equal to the head pressure. The use of an insertable accumulation chamber associated with the GLI, where the liquid can be accumulated even below the perforations, allows the bottom pressure to be reduced to the level of the pumping methods, thus making it possible to maximize a well's production. One of the limitations of this method is the use of conventional mandrels or side pockets below the suspension element of the macaroni tubing, which prevents the operating valve from being replaced with a wire unit.

Document GB2257449A discloses a production system for a subsea well that includes a concentric gas-lift line and a production column, both located within a production riser. A gas-lift mandrel, and associated apparatus, are provided in the tubing suspender to allow gas to be selectively directed down to a lower gas-lift valve located deeper in the wellbore.

Document U.S. Pat. No. 5,785,124A discloses a method for increasing the production of an oil well. The method is comprised of the steps for installing a venturi device inside the well, where the venturi can be associated with a gas-lift mandrel located in the well.

Document WO1996007813A1 presents a gas flow control device for injecting gas into a production column to recover pressure and reduce friction losses so that critical flow can be achieved at low pressures, as well as at higher production pressures. A venturi is used in the side pocket mandrel so that the flow path of the venturi is coaxially aligned with the flow path of the nozzle to provide a continuous flow path.

The aforementioned state of the art does not have the unique characteristics of this invention, which will be presented in detail below.

BRIEF DESCRIPTION OF THE INVENTION

The invention features a concentric mandrel and suspension element, which uses the same gas-lift valve used in a side bag mandrel. The application of the invention is proposed for wells with very low static pressure that operate with an intermittent pneumatic lift, enabling the production in these wells.

The development of a concentric mandrel and the respective macaroni suspension element (1) allows the use of an insertable accumulation chamber, and at the same time allows the replacement of the gas-lift valve to be carried out with a wire unit, thus avoiding rig interventions, which are more expensive and time consuming.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in more detail below, with reference to the attached figures which, in a schematic and non-limiting way, represent examples of the configuration thereof. The drawings include:

FIG. 1 illustrates the concentric mandrel with pneumatic lift valve installed.

FIG. 2 illustrates a well equipped with an insertable chamber with a concentric mandrel.

FIG. 3 illustrates the suspender nipple of the macaroni tubing.

FIG. 4 illustrates a sectional view of the concentric mandrel.

DETAILED DESCRIPTION OF THE INVENTION

An innovative design of concentric mandrel (8) and suspension element (3) was developed, which uses the same gas-lift valve (5) used in the side bag mandrel. The mandrel (8) is installed in the production column just above the plug (16) and couples to the macaroni tubing suspension element (3) (1) which is installed just below the concentric mandrel (8). The macaroni tubing (1) is a production tube, usually of small diameter, and extends well below the plug (16), below which the accumulation chamber (14) is installed, consisting of large diameter production tubes (4), to accumulate the liquid slug. The foot valve (15) is installed at the end of this accumulation chamber (14). The development of the concentric mandrel allows the use of an accumulation chamber in an innovative manner and with higher operational reliability

The suspension element (3) is lowered together with the macaroni tubing (1) during the rig intervention, being installed in the recess of the pipe sleeve (2) with an NU or EU thread. The concentric mandrel (8) is attached just above the suspension element (3) and fits into it when the connection is screwed on.

The bottom assembly has the following elements: concentric nipple (mandrel) (8) for 1.1/2-inch gas lift valve (5) and Nipple suspension element (3) for 1.315-inch NU pipe column (12).

-Figure 1 illustrates the concentric mandrel (8) with gas-lift valve (5) installed. The annular gas inlet (13) occurs from the side (6) and the outlet from below.

FIG. 2 illustrates a well equipped with an insertable chamber (14) with a concentric mandrel (8). The flow of gas passing through the pneumatic lift valve (20) pushes the liquid initially passing through the concentric mandrel itself (8) and (22) and then rises to the surface.

FIG. 3 illustrates the nipple suspension element(3) of the macaroni tubing (1) that is installed below the concentric mandrel (8). In addition to supporting the weight of the macaroni tubing (1), this suspension element (3) has an upper seal that couples to the mandrel and has side holes (21) to allow the passage of liquids and gas during the lifting phase.

FIG. 4 illustrates a sectional view of the concentric mandrel. The gas-lift valve (5) is housed in the center and the passage of liquid and gas occurs during the ascent in the peripheral annulus (21); 

1. CONCENTRIC MANDREL FOR INTERMITTENT PNEUMATIC LIFTING WITH ACCUMULATION CHAMBER, characterized by: comprised of a concentric nipple (8) for the gas-lift valve (5) and a suspension element nipple (3) for the pipe column (1). and a nipple suspension element (3) to be installed in the production column just above the plug (16) and attached to the concentric mandrel (8) and support the macaroni tubing (1), which is installed just below the concentric mandrel (8). 